def main():
    from sys import stdin

    readline = stdin.readline

    X = int(readline().rstrip())

    if X >= 30:
        print('Yes')
    else:
        print('No')
 

main() def main():
    from sys import stdin

    readline = stdin.readline

    X = int(readline().rstrip())

    if X >= 30:
        print('Yes')
    else:
        print('No')
  main from sys import stdin readline = stdin.readline readline stdin.readline stdin readline X = int(readline().rstrip()) X int(readline().rstrip()) int readline().rstrip() ().rstrip () readline rstrip if X >= 30:
        print('Yes')
    else:
        print('No')
  X >= 30 X 30 print('Yes') print 'Yes' print('No') print 'No' main() main def main():
    from sys import stdin

    readline = stdin.readline

    X = int(readline().rstrip())

    if X >= 30:
        print('Yes')
    else:
        print('No')
  def main():
    from sys import stdin

    readline = stdin.readline

    X = int(readline().rstrip())

    if X >= 30:
        print('Yes')
    else:
        print('No')
  main
def main():
    from sys import stdin

    readline = stdin.readline

    X = int(readline().rstrip())

    if X >= 30:
        print('Yes')
    else:
        print('No')
 

main()